Digestive System Embryology Flashcards Preview

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Flashcards in Digestive System Embryology Deck (139):
1

establishes the 3 germ layers of the embryo during 3rd week of development; begins with formation of the primitive streak on the surface of the epiblast

gastrulation

2

all 3 germ layers contribute to the formation of the ____

GI tract

3

_____ of the neuroectoderm become neurons of the ______

neural crest cells; enteric nervous system

4

the mesoderm germ layer contributes to the formation of ____, _____, and _____

connective tissue; muscular components; peritoneal components

5

the endoderm contributes to ____ of GI tract and ____ of glands

epithelium; parenchyma

6

____ covers the ventral surface of the embryo and forms the roof of the yolk sac

endoderm

7

as a result of body folding during the 4th week, the endoderm is incorporated into the embryo to form the _____

primitive gut tube

8

the specific cells of a gland or organ held together by connective tissue called the stroma

parenchyma

9

the endoderm gives rise to specific cells (parenchyma) of glands, such as ____ and the ____ and ____ cells of the ______

hepatocytes; exocrine; endocrine; pancreas

10

the stroma of the glands of the GI tract is derived from _____

visceral mesoderm

11

during cephalocaudal or cranial caudal folding in the ____ direction progresses, the opening of the gut tube into the yolk sac narrows until it forms a small connection called the ____

sagittal; vitelline (yolk sac) duct

12

the vitelline duct is between the ____ and the ____

midgut; yolk sac

13

the vitelline (yolk sac) duct is incorporated into the ____, becomes very narrow, and degenerates with the yolk sac around 2nd-3rd months of development

umbilical cord

14

the foregut extends from the ____ to _____

oropharyngeal membrane; liver outgrowth

15

the oropharyngeal membrane separates the ____ from the ____

stomodeum (primitive oral cavity, derived from ectoderm); pharynx (a part of the foregut, derived from endoderm)

16

in the 4th week, the oropharyngeal membrane ruptures, establishing open connection between ____ and ____

oral cavity; primitive gut

17

the midgut begins _____ and extends to _____

caudal to liver bud; proximal 2/3 of transverse colon

18

hindgut is from _____ to _____

distal 1/3 of transverse colon; cloacal membrane

19

the cloacal membrane separates the ____ (derived from endoderm) from the ____, which is formed by an invaginating pit lined by ectoderm

upper part of the anal canal (derived from endoderm);
lower part of anal canal (from ectoderm)

20

cloacal membrane breaks down in 7th week to create the opening for the ____

anus

21

double layer of peritoneum that encloses an organ and connects it to the body wall

mesentery

22

thin serous membrane that lines walls of abdominal cavity

peritoneum

23

organs which are completely enclosed in mesentery and connected to wall via mesentery

intraperitoneal

24

organ that lies against posterior body wall and is covered with peritoneum on anterior surface only

retroperitoneal

25

the dorsal mesentery is formed via ____ meeting and fusing in the midline

visceral mesoderm layers

26

the _____, ____, and the _____ are suspended from the posterior body wall via dorsal mesentery

caudal part of the foregut; midgut; major part of the hindgut

27

the dorsal mesentery extends from the _____ to the _____

lower end of the esophagus; cloacal region of the hindgut

28

divisions of dorsal mesentery

-dorsal mesogastrium (greater omentum): dorsal mesentery in region of the stomach
-mesoduodenum: dorsal mesentery in region of duodenum
-dorsal mesocolon: dorsal mesentery in region of the colon
-mesentery proper: dorsal mesentery of jejunal and ileal loops

29

ventral mesentery is derived from the ____

septum transversum

30

septum transversum is mesodermal tissue that gives rise to the ____ and _____

central tendon of diaphragm; connective tissue in the liver

31

ventral mesentery exists only in region of ____, ____, and _____

terminal esophagus; stomach; upper part of duodenum

32

liver grows in the ____ of the septum transversum, dividing ventral mesentery into:

mesenchyme; lesser omentum and falciform ligament

33

lesser omentum extends from _____, ____ and _____ to the _____

lower portion of esophagus; stomach; upper portion of the duodenum; liver

34

the falciform ligament extends from ___ to ____

liver; ventral body wall

35

free inferior margin of the falciform ligament; contains obliterated umbilical vein

round ligament of the liver (ligamentum teres hepatis)

36

free margin of lesser omentum connecting duodenum and liver; contains portal triad

hepatoduodenal ligament

37

portal triad components

bile duct, portal vein, and hepatic artery

38

opening that connects omental bursa (lesser sac) with the rest of the peritoneal cavity (greater sac)

epiploic foramen of winslow

39

each gut region is supplied by one of the 3 major arteries off the _____

abdominal aorta

40

foregut is supplied by ____, midgut is supplied by ____, and hindgut is supplied by ____

celiac (trunk) artery; superior mesenteric artery; inferior mesenteric artery

41

foregut derivatives:

-esophagus
-trachea and lung buds
-stomach
-duodenum (proximal to entrance of bile duct)
-liver
-biliary apparatus (hepatic ducts, gallbladder, bile duct)
-pancreas

42

appears at ventral wall of foregut at about the 4th week; is initially in open communication with foregut

respiratory diverticulum (lung bud)

43

foregut divides into _____ (ventral) and _____ (dorsal)

respiratory primordium; esophagus

44

upper 2/3 of esophagus contains:

striated muscle and vagus nerve

45

lower 1/3 of esophagus contains:

smooth muscle and splanchnic plexus

46

when the respiratory diverticulum expands caudally, two longitudinal ridges called ______ separate it from the foregut

tracheoesophageal ridges

47

the tracheoesophageal ridges fuse to form the _____, thereby dividing the foregut into a dorsal portion (_____) and a ventral portion (_____)

tracheoesophageal septum; esophagus; trachea and lung buds

48

the stomach appears as ____ of _____ (4th week)

fusiform dilation; foregut

49

stomach rotates along ____ and _____ axis

longitudinal; anteroposterior

50

stomach rotates _____ around its longitudinal axis

90 degrees clockwise

51

the original left side will now face _____

anteriorly

52

the left vagus nerve will innervate the ____ of the stomach

anterior wall

53

the original right side will now face _____

posteriorly

54

the right vagus nerve will innervate the _____

posterior wall of the stomach

55

concurrent with stomach rotation, the original posterior wall grows faster than the original anterior portion, leading to ____ and ____

greater and lesser curvatures

56

the caudal part of the stomach, or the ____, moves upward and to the right

pylorus

57

the cephalic part of the stomach or the _____, moves slightly downward and to the left

cardia

58

the stomach is attached to the dorsal body wall via _____

dorsal mesogastrium

59

rotation pulls dorsal mesogastrium to the left, creating space behind the stomach called _____

omental bursa (lesser peritoneal sac)

60

appears as mesodermal proliferation between the two leaves of the dorsal mesogastrium (5th week)

spleen primordium

61

connected to body wall in the region of the left kidney

lienorenal ligament

62

connected to stomach

gastrolienal ligament

63

spleen remains ____

intraperitoneal

64

as a result of stomach rotation, the _____ bulges down and grows inferiorly

dorsal mesogastrium

65

the dorsal mesogastrium forms a double-layered sac that extends over the ____ and _____; the layers fuse to form a single sheet that hangs from the greater curvature of the stomach called the _____

transverse colon; small intestine loops; greater omentum

66

the duodenum is formed from the ____ and _____

terminal part of foregut; cephalic part of midgut

67

as stomach rotates, duodenum becomes ____ and rotates to the ____

C-shaped loop; right

68

rotation, together with rapid growth of head of ____, swings duodenum from midline to ___ side of abdomen

pancreas; right

69

____ and ____ press against dorsal body wall and become fixed in ____ position

duodenum; head of pancreas; retroperitoneal

70

a small portion of the duodenum, the ____, near pylorus of stomach, retains mesentery and is ____

duodenal cap; intraperitoneal

71

_____ disappears completely except in region of pylorus of stomach

dorsal mesoduodenum

72

during 2nd month, ___ of duodenum is ____ due to cell proliferation within its wall (called ____)

lumen; obliterated; "solid stage"

73

lumen is ____ (becomes patent) shortly after

recanalized

74

the duodenum is derived from ___ and ____ i.e. its blood supply comes from ____ and _____

foregut; midgut; celiac (trunk) artery; superior mesenteric artery

75

in the middle of the 3rd week, _____ appears at the ____ as an outgrowth of the endodermal epithelium

liver primordium; distal end of the foregut

76

this outgrowth, known as the _____ (______), consists of rapidly proliferating cells that penetrate the _____

liver bud (hepatic diverticulum); septum transversum

77

white hepatic cells invade the septum transversum, the connection between the liver bud and foregut (duodenum) narrows, forming the _____

(common) bile duct

78

a small ventral outgrowth is formed by the bile duct; this outgrowth gives rise to the ____ and ____

gallbladder; cystic duct

79

the pancreas is formed by 2 buds:

a dorsal pancreatic bud and a ventral pancreatic bud

80

the pancreatic buds originate from the ____ lining of the _____

endodermal; duodenum

81

the ____ is within the _____ and the ____ is close to the ____

dorsal bud; dorsal mesentery; ventral bud; bile duct

82

when the duodenum rotates to the right, the _____ also rotates to the right, moving _____

ventral pancreatic bud; dorsally

83

the ventral bud comes to lie immediately ____ and ____ the dorsal bud

below; behind

84

the ventral bud forms:

uncinate process and the inferior part of the head of the pancreas

85

dorsal bud forms:

all other parts of the pancreas

86

formed by distal part of dorsal pancreatic duct and entire ventral pancreatic duct

main pancreatic duct (of Wirsung)

87

main pancreatic duct, together with ____, enters duodenum at _____

bile duct; major (duodenal) papilla

88

formed by proximal part of dorsal pancreatic duct

accessory pancreatic duct (of Santorini)

89

entrance of accessory pancreatic duct

minor (duodenal) papilla

90

In the 3rd month of fetal life, ______ develop from parenchyma & scatter throughout the pancreas

pancreatic islets (of Langerhans)

91

_____ begins at about the 5th month

insulin secretion

92

______ & _____ cells also develop from parenchymal cells

glucagon-secreting; somatostatin-secreting

93

2 major roles of the pancreas

1. enzymatic production and secretion (exocrine)
2. hormonal production and secretion (endocrine)

94

pancreatic islets (of Langerhans) are regions containing ____/_____

endocrine cells; hormone-producing cells (i.e. alpha cells, beta cells, etc.)

95

blood supply to midgut

superior mesenteric a.

96

at ____, midgut communicates with yolk sac via _____

5 weeks; vitelline duct (yolk stalk)

97

in the adult, the midgut begins just distal to the entrance of the _____ into ____

bile duct; duodenum

98

in the adult, the midgut terminates at _____ with ____

junction of proximal 2/3 of transverse colon; distal 1/3

99

rapid elongation of the gut and its mesentery results in formation of the _____

primary intestinal loop

100

loop remains in contact with yolk sac via _____

vitelline duct (yolk stalk)

101

cephalic limb becomes:

-distal part of duodenum
-jejunum
-part of the ileum

102

caudal limb becomes

-lower portion of ileum
-cecum
-appendix
-ascending colon
-proximal 2/3 of transverse colon

103

Development of primary intestinal loop characterized by ______, particularly of the _____

rapid elongation; cephalic limb

104

Due to rapid growth & expansion of ____, abdominal cavity temporarily becomes _____ to contain all the _____

liver; too small; intestinal loops

105

in the ___ week, the intestinal loops enter the extraembryonic cavity in the umbilical cord, known as _____

6th; physiological umbilical herniation

106

As primary intestinal loop lengthens, it concurrently rotates around an axis formed by the ______

superior mesenteric artery

107

midgut rotation is a ____

270 degree counterclockwise rotation (when viewed from the front)

108

first 90 degrees of this rotation occurs during _____

umbilical herniation (about 6th week)

109

remaining 180 degrees of this rotation occurs during _____ into _____

return of intestinal loops; abdominal cavity (10th week)

110

Retraction of herniated loops occurs during the 10th week; it is not precisely known what factors are responsible for return of intestinal loops back to the abdominal cavity; however, it is thought that _____, _____, and _____ play important roles

regression of the mesonephric kidney; reduced growth of the liver; expansion of the abdominal cavity

111

In 2%-4% of individuals, small portion of vitelline duct persists as an outpocketing of the ileum known as ______

Meckel diverticulum (ileal diverticulum)

112

meckel diverticulum is usually ____, but may contain pancreatic tissue or gastric mucosa , which can cause ____, ____, or ____

ulceration; bleeding; perforation

113

Both ends of vitelline duct may develop into fibrous cords, with the middle portion forming a large cyst known as a ______

vitelline cyst (enterocystoma)

114

Intestinal loops may twist around the fibrous strands of the vitelline cyst and become _____, causing _____

obstructed; strangulation

115

Vitelline duct remain patent over its entire length, leading to direct communication between the umbilicus and the intestinal tract; fecal discharge may be found at the umbilicus

vitelline fistula

116

When _____ & _____ colons obtain their final positions, their mesenteries press against ____ of posterior abdominal wall

ascending; descending; peritoneum

117

Via fusion of these layers, the ascending & descending colons are permanently anchored in a _____ position

retroperitoneal (secondarily retroperitoneal)

118

the ____, lower end of ____, and ____ retain their free mesenteries and are _____

appendix; cecum; sigmoid colon; intraperitoneal

119

_____ fuses with posterior wall of greater omentum, but maintains its mobility (intraperitoneal)

transverse mesocolon

120

mesentery of jejunoileal loops

mesentery proper

121

line of attachment of mesentery proper extends from area where duodenum becomes ____, to the _____

intaperitoneal; ileocecal junction

122

transverse mesocolon's line of attachment extends from ____ of ____ to _____ of _____

hepatic flexure; ascending colon; splenic flexure; descending colon

123

hindgut gives rise to:

-distal 1/3 of the transverse colon
-sigmoid colon
-rectum
-upper part of anal canal

124

endoderm of the hindgut forms ____ of the ____ and ____

internal lining; bladder; urethra

125

hindgut supplied by ____

inferior mesenteric artery

126

endoderm-lined cavity covered at its ventral boundary by surface ectoderm

cloaca

127

the boundary between the endoderm and ectoderm forms the ____

cloacal membrane

128

wedge of mesoderm that separates the region between the allantois and hindgut

urorectal septum

129

the tip of the urorectal septum grows inferiorly toward the ____

cloacal membrane

130

the tip of the urorectal septum divides the cloacal membrane into ____ and ____ membranes; partitions the cloaca into ____ (ventrally) and _____ (dorsally)

urogenital; anal; urogenital sinus; anorectal canal

131

at the end of week ____, the cloacal membrane ruptures, creating anal opening for the hindgut and ventral opening for the _____

7; urogenital sinus

132

superior 2/3 of anal canal derived from ____ of ____

endoderm; hindgut

133

inferior 1/3 of anal canal derived from invaginating ____ around ____

ectoderm; proctodeum

134

ectoderm in region of the ____ proliferates and invaginates to create ____

proctodeum; anal pit

135

the cloacal membrane (now called the ____) degenerates and establishes continuity between upper and lower parts of the _____

anal membrane; anal canal

136

junction between ____ and ____ regions of the anal canal is delineated by _____

endodermal; ectodermal; pectinate line

137

epithelium changes from ____ to _____

columnar; stratified squamous epithelium

138

also known as the “anal pit”; it is an ectodermally-lined pit in the terminal portion of hindgut that invaginates to form the lower 1/3 of the anal canal

proctodeum

139

proctodeum initially separated from the rest of the anal canal by the _____, which breaks down to permit continuity between the two parts of the canal

anal membrane